Officials announced the main event on Friday. Miocic (18-2) will be seeking his fourth consecutive heavyweight title defense. Cormier (20-1), the UFC's light heavyweight champion, will move up in weight.
When asked by TMZ Sports if he had any reservations about moving up a weight class, Cormier said, "Nah -- I just want to fight. And plus, it's such a big opportunity that it's one of those you can't really pass up when it's offered to you."
"I've never been afraid of a fight," Cormier said. "It was always about whether or not it worked in terms of what I was trying to do and what my teammate had going."
The UFC 226 pay-per-view event will take place at T-Mobile Arena.
It's one of several "champion vs. champion" title fights the UFC is seeking this year. UFC president Dana White has also expressed interest in bantamweight champion TJ Dillashaw moving down to face flyweight titleholder Demetrious Johnson. He has also referred to a fight between female bantamweight champion Amanda Nunes and featherweight champion Cris "Cyborg" Justino as "the fight to make."
"It's a big deal, a great opportunity to fight the greatest heavyweight champion of all time and try to submit myself as one of the best fighters to ever do it," Cormier said.
Before headlining UFC 226, Miocic and Cormier will serve as opposing coaches on "The Ultimate Fighter" reality series, which is set to feature cast members with undefeated records.
Miocic, of Cleveland, is coming off a successful title defense against Francis Ngannou at UFC 220 last weekend. The 35-year-old set a new UFC record for the most consecutive heavyweight title defenses. Fighting out of American Kickboxing Academy in San Jose, California, Cormier also defended his title at UFC 220, as he knocked out Volkan Oezdemir in the second round. Cormier's only professional loss is against Jon Jones, at UFC 182 in 2015. He intends to retire by March 2019.